OCD is primarily a disorder of the young athlete. The usual age of presentation is 12 to 14 years of age, compared with 9 to 10 for Panner’s disease. Males are affected more often than females, but there is a high prevalence in young female gymnasts and competitive cheerleaders. The dominant arm is most often involved with bilateral involvement in 5% to 20% of patients. There is usually a history of overuse, most commonly throwing, repetitive impact, or overhead sports. Early on, the symptoms may be obscure, with pain location difficult to determine. It most often begins with some mild aching after activity. Most patients will try self-medicating with anti-inflammatory medicine and ice, which may provide some temporary relief. Symptoms will often worsen very slowly. On presentation, the history is most often that of pain that increases with increased activity, loss of motion, and swelling on the lateral side of the elbow. Additional complaints of popping, clicking, or sudden “giving way,” especially with load bearing, may also be present.

The classic physical findings include loss of terminal extension and swelling along the posterolateral joint line along with inflammation of the normal posterolateral plica. Valgus extension overload testing will produce pain over the lateral aspect of the elbow and result in a measurable increase in the loss of terminal extension. This is one of the key differentiating factors in the physical examination of OCD. Most throwing or hyperextension overuse injuries when tested in valgus will have the primary component of pain along the medial aspect of the elbow: the medial apophysis, the medial ulnar collateral ligament, or the flexor-pronator muscle. These may coexist with the OCD, but in OCD patients these instability stress maneuvers, especially the moving valgus overload test, will result in pain more on the lateral than on the medial side.

The initial testing involves standard PA and lateral radiographs. These will usually show the classic findings of radiolucency in the central aspect of the capitellum. There may be a small area of increased opacity in the center of the radiolucency (Fig. 33.1). In the later stages, loose bodies may be present.

Additional testing may be warranted early in the course of treatment. Computed tomography (CT), CT arthrograms, and ultrasound have all been utilized in the evaluation of these lesions. However, MRI has become the standard modality for evaluation of these lesions. The key points to evaluate that will assist in determining appropriate management include the extent of the bone involvement, the integrity of the overlying cartilage cap, and the presence of loose bodies. Early lesions will show change on T1-weighted MRI images, but no change on T2 sequences. The cartilage covering will be intact, indicating an improved prognosis. Advanced lesions will show changes on both T1 and T2 images and may demonstrate a loose in situ bone fragment (Fig. 33.2). Assessment of the
integrity of the cartilage cap remains paramount. As the condition advances, the cartilage cap is violated, allowing synovial fluid between the fragment and the remaining capitellum. This jeopardizes any chance at union with fixation and may result in one or more loose fragments being shed into the joint. However, the simple presence of loose bodies does not definitively define a rupture of the cartilage, so MRI assessment remains necessary. The lesion that advances to the lateral edge or “shoulder” of the capitellum is a much more severe injury that requires more extensive reconstructive surgery (Fig. 33.3). In the most advanced cases, three-dimensional (3D) imaging may be helpful to define the loss of this critical lateral cortex (Fig. 33.4A-C).